objective: to investigate the association between household food and nutrition security status and breastfeeding among children under 2 years old. methods: data were analyzed from 1,635 children under 2 years old who had participated in the brazilian national demographic and health census in 2006. the outcome (breastfeeding) was evaluated according to data on the children's food intake on the day before the interview and food insecurity was assessed using the brazilian food insecurity scale. results: approximately 58% of children were breastfeeding and 47% were living in households with food insecurity. there was an association between breastfeeding and households in a state of food insecurity, but only for children older than 12 months. in this age group, breastfeeding prevalence was higher (41%) among children living in households with food and nutrition insecurity than those who lived in households considered secure (29%). there were no associations between food insecurity and breastfeeding in the first year of life or early introduction of foods other than breastmilk. conclusion: food insecurity is associated with a higher prevalence of breastfeeding in the second year of life.